CN113300023B - Energy storage system and condensation prevention control method thereof - Google Patents

Abstract

The present invention provides an energy storage system and its anti-condensation control method. Firstly, according to the detected ambient temperature and relative humidity inside each battery module, respectively determine the dew point temperature of each battery module; and determine the internal temperature of each battery module. The surface temperature of the object in contact with each battery cell; then, for each battery module, determine the level of the difference between the dew point temperature and the surface temperature in the preset classification; and then control the liquid cooling system according to the level. action to increase the surface temperature of the corresponding battery module to avoid condensation. That is to say, the present invention prevents condensation through the action of the liquid cooling system itself, avoiding a series of problems caused by the solution of desiccant, and can perform corresponding actions according to the corresponding level, with controllable effect and high reliability.

Description

An energy storage system and anti-condensation control method thereof

technical field

The invention relates to the technical field of energy storage systems, in particular to an energy storage system and an anti-condensation control method thereof.

Background technique

The heat dissipation principle of the existing energy storage system is mainly to exchange and take away the heat generated by the battery through the flow of low-temperature substances (air, cooling fluid) over the surface of the battery. However, while the battery is dissipating heat, due to the low temperature of the cooling medium and the high ambient temperature, when the air with a higher temperature encounters a low-temperature object, condensation will form on the surface of the low-temperature object.

Due to the battery technology, the positive electrode of the battery itself and the metal casing are connected through low impedance or directly. When condensation is formed on the surface of the low-temperature object, the metal casings of multiple batteries located on the same low-temperature object inside the module box will be connected together to form a short circuit through condensed water, as shown in Figure 1; when the metal casings of different batteries are connected After being together, the positive and negative poles of the related cells will form a short circuit, which may cause thermal runaway of the cells, fire and other severe accidents. The short-circuit equivalent circuit is shown in Figure 2.

In order to avoid the occurrence of the above situation, the existing solution is to add a desiccant inside the module box, and the desiccant absorbs the moisture in the air inside the module to prevent condensation. However, because the module itself will exchange air with the outside through the breathing valve to balance the pressure inside and outside the module, during the air exchange process, the outside air of the module will enter the inside of the module; moreover, the desiccant absorbs water frequently for a long time, On the one hand, the drying performance of the desiccant will decrease. On the other hand, the desiccant absorbs a large amount of water. When the temperature rises, the moisture absorbed in the desiccant will evaporate again, which will increase the relative humidity inside the module box.

Contents of the invention

In view of this, the present invention provides an energy storage system and its anti-condensation control method to avoid condensation inside the liquid cooling module, and its reliability is higher than that of the desiccant solution in the prior art.

To achieve the above object, the present invention provides the following technical solutions:

The first aspect of the present invention provides an anti-condensation control method for an energy storage system, the energy storage system includes at least one battery module, and each of the battery modules is dissipated by a liquid cooling system; the energy storage system Anti-condensation control methods include:

Determine the dew point temperature of each of the battery modules according to the detected ambient temperature and relative humidity inside each of the battery modules;

Determining the surface temperature of the object in contact with each battery cell inside each battery module;

For each of the battery modules, respectively determine the level of the difference between the dew point temperature and the surface temperature in the preset classification;

According to the grade, the liquid cooling system is controlled to perform corresponding actions to increase the surface temperature of the corresponding battery module to avoid condensation.

Optionally, according to the detected ambient temperature and relative humidity inside each of the battery modules, respectively determine the dew point temperature of each of the battery modules, including:

For each of the battery modules, the dew point temperature is obtained through calculation or table lookup according to the corresponding ambient temperature and the relative humidity.

Optionally, determining the surface temperature of the object in contact with each battery cell inside each battery module includes:

For each of the battery modules, directly detect the surface temperature of the heat-conducting medium at the bottom of each of the battery cells; or,

The surface temperature of the liquid cooling plate inside each battery module or the coolant temperature of the liquid cooling system is respectively detected, and converted to obtain the surface temperature of each battery module.

Optionally, determining the grade of the difference between the dew point temperature and the surface temperature in the preset classification includes:

judging whether the difference is greater than a second threshold;

If the difference is less than or equal to the second threshold, then judging whether the difference is greater than a first threshold; the first threshold is less than the second threshold;

If the difference is greater than the first threshold, it is determined that the grade belongs to the second grade;

If the difference is less than or equal to the first threshold, it is determined that the grade belongs to the first grade.

Optionally, according to the grade, the liquid cooling system is controlled to perform corresponding actions, including:

If the level belongs to the second level, when the liquid cooling system is operating in the cooling mode, control the liquid cooling system to stop cooling; or, when the liquid cooling system is not operating in the cooling mode , controlling the liquid cooling system to operate in a heating mode;

If the grade belongs to the first grade, the liquid cooling system is controlled to operate in a heating mode.

Optionally, controlling the liquid cooling system to operate in a heating mode includes:

Control the heating resistors in the corresponding pipelines in the liquid cooling system to work.

Optionally, controlling the liquid cooling system to stop cooling includes:

The liquid cooling unit controlling the liquid cooling system stops running.

Optionally, when the input end of each liquid cooling plate of the liquid cooling system is provided with an electronically controlled valve, in the step of determining that the difference between the dew point temperature and the surface temperature belongs to a grade in the preset classification, Before judging whether the difference is greater than the second threshold, it also includes:

judging whether the difference is greater than a third threshold; the third threshold is greater than the second threshold;

If the difference is less than or equal to a third threshold, then execute the step of judging whether the difference is greater than a second threshold, and if the difference is greater than the second threshold, then determine that the level belongs to the third level.

Optionally, the step of controlling the liquid cooling system to perform corresponding actions according to the grade further includes:

If the grade belongs to the third grade, the valve opening of the corresponding electronically controlled valve is adjusted according to the preset relationship between the difference and the valve opening.

The second aspect of the present invention provides an energy storage system, including: a control module, a detection module, a liquid cooling system, and at least one battery module; wherein:

The detection module is at least used to detect the ambient temperature and relative humidity inside each battery module, and the surface temperature or its representative temperature of the object in contact with each battery cell inside each battery module;

The input terminal of the control module is connected to the output terminal of the detection module, the output terminal of the control module is connected to the control terminal of the liquid cooling system, and the control module is used to perform the above-mentioned steps described in any paragraph of the first aspect. The anti-condensation control method of the energy storage system described above.

Optionally, the liquid cooling system includes: a liquid cooling unit, multiple transmission pipelines, and multiple liquid cooling plates;

The liquid cooling unit provides a cooling liquid circulation function for each of the liquid cooling plates through the corresponding transmission pipeline;

The liquid cooling plate is arranged in the battery module to dissipate heat for each battery cell inside the battery module.

Optionally, the liquid cooling system further includes: a plurality of electronically controlled valves respectively arranged at the input ends of each of the liquid cooling plates;

The electric control valve is controlled by the control module.

Optionally, the battery module includes: an upper cover, a lower box and a plurality of batteries;

Each of the battery cells is respectively arranged in the space between the lower box body and the upper cover;

In addition, each battery cell is arranged on the surface of the lower box through the heat conducting medium and the corresponding liquid cold plate in sequence.

Optionally, in the battery module, each of the battery cells is sequentially connected in series.

Optionally, each of the battery modules is connected in parallel.

Based on the anti-condensation control method of the energy storage system provided by the present invention, it first determines the dew point temperature of each battery module according to the detected ambient temperature and relative humidity inside each battery module; and determines the temperature of each battery module. The surface temperature of the object in contact with each battery cell; then, for each battery module, determine the level of the difference between the dew point temperature and the surface temperature in the preset classification; and then control the liquid cooling system according to the level. action to increase the surface temperature of the corresponding battery module to avoid condensation. That is to say, the present invention prevents condensation through the action of the liquid cooling system itself, avoiding a series of problems caused by the solution of desiccant, and can perform corresponding actions according to the corresponding level, with controllable effect and high reliability.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only It is an embodiment of the present invention, and those skilled in the art can also obtain other drawings according to the provided drawings without creative work.

FIG. 1 is a schematic diagram of battery cell series connection provided by the prior art;

Fig. 2 is the short-circuit equivalent circuit diagram of the cell provided by the prior art;

3 is a schematic structural diagram of a liquid cooling system provided by an embodiment of the present invention;

Fig. 4 is a flowchart of an anti-condensation control method for an energy storage system provided by an embodiment of the present invention;

Fig. 5 is a specific flowchart of an anti-condensation control method for an energy storage system provided by an embodiment of the present invention;

Fig. 6 is another structural schematic diagram of the liquid cooling system provided by the embodiment of the present invention;

Fig. 7 is another specific flowchart of an anti-condensation control method for an energy storage system provided by an embodiment of the present invention;

Fig. 8 is a schematic structural diagram of an energy storage system provided by an embodiment of the present invention;

Fig. 9 is a partial structural schematic diagram of a battery module provided by an embodiment of the present invention.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

In this application, the term "comprises", "comprises" or any other variation thereof is intended to cover a non-exclusive inclusion such that a process, method, article, or apparatus comprising a set of elements includes not only those elements, but also includes none. other elements specifically listed, or also include elements inherent in such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the process, method, article or apparatus comprising said element.

The invention provides an anti-condensation control method of an energy storage system to avoid condensation inside a liquid cooling module, and its reliability is higher than that of a desiccant solution in the prior art.

The energy storage system includes at least one battery module, and each battery module is dissipated by a liquid cooling system. Inside the battery module, a corresponding liquid cooling plate is respectively configured to dissipate heat for each battery cell in the battery module; as shown in Figure 3, in the liquid cooling system, the liquid cooling unit passes the corresponding transmission pipeline for Each liquid cold plate provides coolant circulation.

As shown in Figure 4, the anti-condensation control method of the energy storage system includes:

S101. Determine the dew point temperature of each battery module according to the detected ambient temperature and relative humidity inside each battery module.

First, a temperature sensor that can collect ambient temperature and a relative humidity sensor that can collect relative humidity are installed inside the battery module; then the ambient temperature T1 and relative humidity RH1 inside the corresponding battery module can be obtained according to the collection, and then according to T1 and RH1 can be Calculate or directly look up the table to obtain the dew point temperature T3 of the corresponding battery module under the current conditions. Wherein, when calculating according to T1 and RH1, it can be specifically calculated by using the Lawrence formula: Td=1/((1/T)-(lnRH)/5423) under the thermodynamic temperature scale, but it is not limited thereto.

S102. Determine the surface temperature of an object in contact with each battery cell inside each battery module.

For each battery module, inside the battery module, there will be a corresponding heat-conducting medium between the surface of the liquid-cooled plate and each battery cell. The heat-conducting medium is an object that the battery core directly contacts. If the surface temperature T2 of the heat transfer medium is lower than the dew point temperature T3, condensation will occur, which will lead to a short circuit. Therefore, it is necessary to detect the surface temperature of the heat transfer medium.

When detecting the surface temperature of the heat-conducting medium, the surface temperature of the heat-conducting medium at the bottom of each cell can be detected directly through a temperature sensor arranged on the surface of the heat-conducting medium; To detect the surface temperature of the corresponding liquid cooling plate, and then convert it to obtain the surface temperature of the heat transfer medium; it can also be converted according to the coolant temperature of the liquid cooling system to obtain the surface temperature of each battery module; Other methods can be used, which are not limited here, and can be determined according to the specific application environment, all of which are within the protection scope of the present application.

It should be noted that the sequence of steps S101 and S102 is not limited, they can be executed one after the other, or at the same time; in practical applications, the two steps can each have their own execution cycle, depending on the specific application environment , are all within the protection scope of this application.

S103. For each battery module, respectively determine the grade to which the difference between the dew point temperature and the surface temperature belongs in the preset classification.

Theoretically, when the above-mentioned surface temperature T2 is less than or equal to the dew point temperature T3, condensation will occur, and the more the surface temperature T2 is higher than the dew point temperature T3, the lower the possibility of condensation will occur. That is to say, according to the size of the temperature difference between the two, it can indicate the level of the possibility of condensation; the smaller the surface temperature T2, that is, the closer it is to the dew point temperature T3, the higher the level of the possibility of condensation; The higher the temperature T2 is, ie the farther it is from the dew point temperature T3, the lower is the level of its possibility of condensation.

S104. According to the grade, control the liquid cooling system to perform corresponding actions to increase the surface temperature of the corresponding battery module to avoid condensation.

When the possibility of condensation occurring in the battery module is low, less intensive measures can be taken to avoid condensation, such as controlling the temperature of the corresponding liquid cold The heat release caused by the core work can make the temperature of the liquid cold plate rise to a certain extent, thereby avoiding the expansion of the difference between the surface temperature T2 and the dew point temperature T3, and avoiding condensation.

When the possibility of condensation in the battery module is high, it is necessary to take strong measures to avoid condensation, such as controlling the temperature rise of the corresponding liquid cold plate to quickly increase the gap between the surface temperature T2 and the dew point temperature T3 difference, avoid condensation.

The anti-condensation control method provided in this embodiment prevents condensation through the action of the liquid cooling system itself, avoiding a series of problems caused by the use of desiccant solutions, and can perform corresponding actions according to the corresponding level, and the effect is controllable , High reliability. In addition, the liquid cooling unit of the liquid cooling system itself is used to prevent condensation, which can also avoid adding vulnerable materials, and can greatly save maintenance cycles.

On the basis of the previous embodiment, this embodiment is based on the idea that there will be a delay in the temperature rise of the coolant, so a temperature difference needs to be set, and a specific classification method is given:

Specifically, step S103 includes as shown in FIG. 5:

S301. Determine whether the difference is greater than a second threshold.

The difference is T2-T3; the second threshold is ΔT2, and its specific value is not limited, as long as it is greater than 0.

That is, step S301 is to determine whether T2-T3>ΔT2 holds.

If the difference is greater than the second threshold, that is, if T2-T3>ΔT2 holds true, it indicates that the surface temperature T2 of the heat transfer medium fails to reach the dew point temperature R3 of the current environment, and condensation will not occur on the surface of the heat transfer medium, and you can return to the step S101, re-acquire the current environmental condition; and if the difference is less than or equal to the second threshold, that is, if T2-T3>ΔT2 does not hold, then execute step S302.

S302. Determine whether the difference is greater than a first threshold.

The first threshold ΔT1 is smaller than the second threshold ΔT2. The first threshold ΔT1 is a number greater than 0, and the specific value can be adjusted according to specific working conditions, which is not limited here.

That is, step S302 is to determine whether T2-T3>ΔT1 holds true.

If the difference is greater than the first threshold, that is, if T2-T3>ΔT1 is established, it is determined that the level belongs to the second level; if the difference is less than or equal to the first threshold, that is, if T2-T3>ΔT1 is not established, then it is determined It belongs to the first level.

The first level is higher than the second level, that is, when the level is the first level, it means that the possibility of condensation is very high at this time, and the temperature of the liquid cold plate needs to be adjusted quickly; when the level is the second level, it means At this time, the possibility of condensation is smaller than that of the first stage, and the temperature regulation of the liquid cold plate can be reduced.

Specifically, as shown in FIG. 5, step S104 includes:

If the level belongs to the second level, if the liquid cooling system is running in cooling mode, execute step S401; or, if the liquid cooling system is not running in cooling mode, execute step S402. If the belonging level is the first level, step S402 is directly performed.

S401. Control the liquid cooling system to stop cooling.

S402. Control the liquid cooling system to operate in a heating mode.

In practical applications, step S401 may be: controlling the liquid cooling unit of the liquid cooling system to stop running. And step S402 may be: controlling the heating resistors in the corresponding pipelines in the liquid cooling system to work. This is only a corresponding example, and is not limited thereto. For example, step S402 may also be heated through the operation of a compressor, depending on the specific application environment, all within the protection scope of the present application.

It is worth noting that the setting of ΔT1 and ΔT2 is to consider the difference between T2 and T3. If there is still a large difference between T2 and T3, which is greater than ΔT2, then just stop the liquid cooling unit such as the water cooling machine. Yes, the battery can be used to heat the coolant during operation, which can avoid the power consumption caused by turning on the heating function. When the difference between T2 and T3 is small, between ΔT1 and ΔT2, the temperature of the coolant can be increased by stopping the liquid cooling unit or starting heating. There are two possible states here: one may be The liquid-cooled unit is cooling, just stop cooling at this time, the heating of the battery can heat the coolant, increase the temperature of the coolant, and prevent condensation; another possibility is that the liquid-cooled unit is not cooling, at this time in order to make the coolant temperature When it is elevated, it is necessary to turn on the heating mode to heat the coolant. And when the difference between T2 and T3 is very small, less than ΔT1, considering the temperature rise delay, no matter what state the liquid cooling unit is in, it is necessary to turn on the heating function in time to heat the coolant.

In this embodiment, the liquid cooling unit is linked by the ambient temperature and relative humidity inside the module and the surface temperature of the heat transfer medium, and through the above control process, condensation inside the battery module is automatically prevented. In addition, the size of the difference between T2 and T3 is classified into grades, so that the cooling liquid temperature adjustment process is smooth, and the energy saving effect is considered at the same time, which is conducive to popularization.

On the basis of the above-mentioned embodiments, preferably, the input ends of each liquid cooling plate of the liquid cooling system can also be provided with corresponding electric control valves, as shown in Figure 6; furthermore, through the electric control valves, individual The battery modules are independently adjusted, and the surface temperature T2 of the heat transfer medium can also be adjusted by adjusting the coolant flow rate of the individual battery modules.

Referring to FIG. 7, another classification method is provided. On the basis of FIG. 5, in step S103, before performing step S301 and judging whether the difference is greater than the second threshold, it also includes:

S300. Determine whether the difference is greater than a third threshold ΔT3.

The third threshold ΔT3 is greater than the second threshold ΔT2; its specific value is not limited, and it depends on its application environment.

If the difference is greater than the third threshold ΔT3, that is, if T2-T3>ΔT3 holds, return to step S101.

If the difference is less than or equal to the third threshold ΔT3, that is, if T2-T3>ΔT3 does not hold, step S301 will be performed, and if the difference is greater than the second threshold, it will be determined that the level belongs to the third level.

Correspondingly, in step S104, it also includes:

If the belonging level is the third level, execute step S403.

S403. According to the preset relationship between the difference and the valve opening, adjust the valve opening of the corresponding electric control valve.

The preset relationship may be a simple linear relationship, mainly depending on the specific setting of the electronically controlled valve, the more optional values of the valve opening, the finer the control process and result.

For other processes and principles, reference may be made to the foregoing embodiments, and details will not be repeated here.

In this embodiment, the difference between T2 and T3 is divided into three levels. The control operations under the three levels are: adjusting the valve opening, stopping cooling, and turning on heating. This operation mode can make the cooling liquid temperature Adjustment is smoother.

Another embodiment of the present invention also provides an energy storage system, as shown in FIG. 8 , including: a control module 101, a detection module 102, a liquid cooling system, and at least one battery module 103; wherein:

In practical applications, in each battery module 103 , preferably, each cell is connected in series; and when the number of battery modules 103 is greater than 1, each battery module 103 is preferably connected in parallel.

The detection module 102 is at least used to detect the ambient temperature and relative humidity inside each battery module 103, and the surface temperature or representative temperature of the object contacted by each battery cell inside each battery module 103; The surface temperature of the liquid cooling plate inside the group or the coolant temperature of the liquid cooling system is not specifically limited here.

The detection module 102 may include a temperature sensor and a relative humidity sensor disposed inside each battery module 103, and a temperature sensor and a cooling liquid disposed on the surface of the object or the surface of the liquid cooling plate that each cell contacts inside the battery module 103 At least one of the temperature sensors; it depends on the specific application environment, and all are within the protection scope of the present application.

The input terminal of the control module 101 is connected to the output terminal of the detection module 102, and the output terminal of the control module 101 is connected to the control terminal of the liquid cooling system. Condensation control method.

As shown in Figure 3, the liquid cooling system includes: a liquid cooling unit, multiple transmission pipelines, and multiple liquid cooling plates; where:

The liquid cooling unit provides cooling liquid circulation function for each liquid cold plate through the corresponding transmission pipeline.

The liquid cold plate is arranged in the battery module 103 to dissipate heat for each battery cell inside the battery module 103 .

Referring to Fig. 6, the liquid cooling system may also include: a plurality of electronic control valves respectively arranged at the input ends of each liquid cooling plate; the electronic control valves are controlled by the control module 101, so that the control module can realize the anti-condensation control method.

Referring to FIG. 9, the battery module 103 includes: an upper cover (not shown in the figure), a lower box 301 and a plurality of batteries 302; wherein:

Each battery cell 302 is respectively disposed in the space between the lower case 301 and the upper cover.

Moreover, each battery cell 302 is arranged on the surface of the lower box 301 through the heat conduction medium and the corresponding liquid cooling plate in sequence.

As shown in Figure 9, the battery cells 302 are evenly arranged on the lower box body 301, and liquid cooling plates, heat conduction pads, heat insulation foam, etc. can be placed between the battery cells 302 and the lower box body 301, which will not be done here. The limitation depends on the specific application environment and is within the protection scope of the present application.

Since the temperature of the coolant passing through the liquid cooling plate above the lower box 301 of the module is generally relatively low, the temperature will be lower than the air temperature in the module under normal conditions. When the relative humidity and temperature of the air inside the module reach a certain value, When the corresponding dew point temperature is greater than or equal to the surface temperature of the heat transfer medium on the liquid cooling plate, condensed water will form on the surface of the heat transfer medium. The positive electrode of the battery cell is generally connected to the metal shell of the battery cell through low impedance, and some even connect the positive electrode directly to the metal shell. The metal shells of the battery cells are connected together through condensed water to form a short circuit, as shown in Figure 1; when the metal shells of the battery cells are connected together, the positive and negative electrodes of the battery cells will form a short circuit, which may cause thermal runaway of the battery cells and fire and other severe accidents, the equivalent circuit is shown in Figure 2.

In order to avoid the above situation, this embodiment uses the control module 101 to implement the anti-condensation control method provided by any of the above-mentioned embodiments, and then uses the liquid cooling unit of the liquid cooling system itself to realize anti-condensation. For the specific process and principle of the method, refer to the above-mentioned embodiments, and details will not be repeated here.

Each embodiment in this specification is described in a progressive manner, the same and similar parts of each embodiment can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the system or the system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and for related parts, please refer to the part of the description of the method embodiment. The systems and system embodiments described above are only illustrative, and the units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is It can be located in one place, or it can be distributed to multiple network elements. Part or all of the modules can be selected according to actual needs to achieve the purpose of the solution of this embodiment. It can be understood and implemented by those skilled in the art without creative effort.

Professionals can further realize that the units and algorithm steps of the examples described in conjunction with the embodiments disclosed herein can be implemented by electronic hardware, computer software or a combination of the two. In order to clearly illustrate the possible For interchangeability, in the above description, the composition and steps of each example have been generally described according to their functions. Whether these functions are executed by hardware or software depends on the specific application and design constraints of the technical solution. Skilled artisans may use different methods to implement the described functions for each specific application, but such implementation should not be regarded as exceeding the scope of the present invention.

For the above description of the disclosed embodiments, the features recorded in each embodiment in this specification can be replaced or combined with each other, so that those skilled in the art can realize or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention will not be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (11)

1. An anti-condensation control method for an energy storage system, characterized in that the energy storage system includes at least one battery module, and each of the battery modules is dissipated by a liquid cooling system; the anti-condensation of the energy storage system Condensation control methods include: Determine the dew point temperature of each of the battery modules according to the detected ambient temperature and relative humidity inside each of the battery modules; Determining the surface temperature of the object in contact with each battery cell inside each battery module; For each of the battery modules, respectively determine the level of the difference between the dew point temperature and the surface temperature in the preset classification; wherein, the difference is pre-divided into multiple levels; the difference is The difference between the surface temperature minus the dew point temperature; according to the grade, control the liquid cooling system to perform corresponding actions to increase the surface temperature of the corresponding battery module to avoid condensation; If the grade belongs to the first grade, then controlling the liquid cooling system to operate in a heating mode; If the level belongs to the second level, when the liquid cooling system is operating in the cooling mode, control the liquid cooling system to stop cooling; or, when the liquid cooling system is not operating in the cooling mode , controlling the liquid cooling system to operate in a heating mode; If the grade belongs to the third grade, then adjust the valve opening of the corresponding electric control valve according to the preset relationship between the difference and the valve opening; cold plate input; Wherein, determining the grade of the difference between the dew point temperature and the surface temperature in the preset classification includes: judging whether the difference is greater than a second threshold; If the difference is less than or equal to the second threshold, then judging whether the difference is greater than a first threshold; the first threshold is less than the second threshold; If the difference is greater than the first threshold, it is determined that the grade belongs to the second grade; If the difference is less than or equal to the first threshold, it is determined that the grade belongs to the first grade; judging whether the difference is greater than a third threshold; the third threshold is greater than the second threshold; If the difference is less than or equal to a third threshold, then execute the step of judging whether the difference is greater than a second threshold, and if the difference is greater than the second threshold, then determine that the level belongs to the third level. 2. The anti-condensation control method of the energy storage system according to claim 1, wherein the dew point of each of the battery modules is respectively determined according to the detected ambient temperature and relative humidity inside each of the battery modules temperature, including: For each of the battery modules, the dew point temperature is obtained through calculation or table lookup according to the corresponding ambient temperature and the relative humidity. 3. The anti-condensation control method of the energy storage system according to claim 1, wherein determining the surface temperature of the object in contact with each battery cell inside each battery module includes: For each of the battery modules, directly detect the surface temperature of the heat-conducting medium at the bottom of each of the battery cells; or, The surface temperature of the liquid cooling plate inside each battery module or the coolant temperature of the liquid cooling system is respectively detected, and converted to obtain the surface temperature of each battery module. 4. The anti-condensation control method of the energy storage system according to claim 1, wherein controlling the liquid cooling system to operate in a heating mode comprises: Control the heating resistors in the corresponding pipelines in the liquid cooling system to work. 5. The anti-condensation control method of the energy storage system according to claim 1, wherein controlling the liquid cooling system to stop cooling comprises: The liquid cooling unit controlling the liquid cooling system stops running. 6. An energy storage system, characterized by comprising: a control module, a detection module, a liquid cooling system, and at least one battery module; wherein: The detection module is at least used to detect the ambient temperature and relative humidity inside each of the battery modules, and the surface temperature of the object in contact with each battery cell inside each of the battery modules or its representative temperature; the representative temperature is The surface temperature of the liquid cooling plate inside the battery module or the temperature of the coolant in the liquid cooling system; The input end of the control module is connected to the output end of the detection module, the output end of the control module is connected to the control end of the liquid cooling system, and the control module is used to perform any one of claims 1-5. The anti-condensation control method of the energy storage system described in the item. 7. The energy storage system according to claim 6, wherein the liquid cooling system comprises: a liquid cooling unit, a plurality of transmission pipelines and a plurality of liquid cooling plates; The liquid cooling unit provides a cooling liquid circulation function for each of the liquid cooling plates through the corresponding transmission pipeline; The liquid cooling plate is arranged in the battery module to dissipate heat for each battery cell inside the battery module. 8. The energy storage system according to claim 7, characterized in that, The electric control valve is controlled by the control module. 9. The energy storage system according to claim 7, wherein the battery module comprises: an upper cover, a lower box and a plurality of battery cells; Each of the battery cells is respectively arranged in the space between the lower box body and the upper cover; In addition, each battery cell is arranged on the surface of the lower box through the heat conducting medium and the corresponding liquid cold plate in sequence. 10. The energy storage system according to claim 9, characterized in that, in the battery module, each of the battery cells is sequentially connected in series. 11. The energy storage system according to any one of claims 6-10, wherein each of the battery modules is connected in parallel.

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